The present invention is related to a HVAC system for use in an automobile. In particular, the HVAC system uses a compressor capacity control that enhances the overall efficiency of the compressor operation.
Background
Passenger comfort and fuel efficiency have set forth increasing demands on automotive heating, ventilating and air-conditioning (HVAC) systems. It is a primary goal of most HVAC systems to provide a more efficient means for providing climate control to an automobile.
As a result, newer and improved automotive HVAC systems are configured to make use of available energy sources without placing an additional load onto the vehicle system.
Moreover, and as vehicles become more fuel efficient, energy loading upon the vehicles operating system becomes a critical feature of design aspects.
This is particularly true in a hybrid vehicle. A Hybrid Vehicle is a vehicle that has two sources of propulsion. A hybrid electric vehicle (HEV) is a vehicle wherein one of the sources of propulsion is electric and the other source of propulsion may be derived from fuel cells or an internal combustion engine (ICE) that burns diesel, gasoline or any other source of fuel.
In particular, the HVAC system of an automobile utilizes a compressor that is either mechanically or electrically driven to circulate an automobile refrigerant to heat and or cool the interior passenger compartment of an automobile. Typically, the compressor is activated in response to a user demand such as a cooling request which will activate the compressor. In this system the compressor will be activated and/or deactivated in response to a user setting as well as a sensor placed within the vehicle compartment or in an appropriate location along the refrigerant line.
Accordingly, there is no control over the compressor operation other than its activation and deactivation which causes a significant load to be applied to the vehicles operating system.
Moreover, and referring in particular to compressors which are mechanically coupled to the automobile""s engine, the operation of the compressor is directly proportional to the speed (RPM) of the vehicles engine. Accordingly, there is no separate control of the compressors operation other than switching it on and off. In addition, the highest amount of demand required from the compressor is generally at times when the automobile is at idle (i.e. traffic jams and city driving conditions), and accordingly, the engine""s speed is lowest.
In a recent attempt to address this problem larger capacity compressors having their operational capacity limited by a compressor control valve were produced, however, these compressors still offered no means for varying the compressor capacity.
Therefore there is a need for control system wherein the operation of the compressor is optimized in order to minimize its operational load upon the vehicle as well as increased the overall efficiency of the compressor and the vehicle.
It is therefore an object of the invention to provide an improvement in the performance of a HVAC system of an automotive vehicle.
Another object is to provide a method and apparatus for supplementing and/or improving the HVAC system of an automotive vehicle.
Another object of the present invention is to provide a method and apparatus for improving the HVAC system of an automobile without affecting the energy load and accordingly the fuel efficiency of the automobile engine.
Another object of the present invention is to link the compressor control to the temperature control and ambient temperature. In this embodiment the temperature control defines the set point of airflow temperature in the HVAC unit in response to a user selection.